Fluid cylinder unit cushion structure

ABSTRACT

A fluid cylinder unit cushion structure having a cylinder with a piston slidable therein against a stop to present a space between the head end of the cylinder and the piston. The fluid port is in the cylinder head end, and the piston carries a spring type of valve which seats over the fluid port when the piston is in its end limit position at the head end. The spring also has clearance for moving off the fluid port when the piston is in its end limit position and when the fluid pressure is reversed to get flow into the cylinder through the port and thereby return the piston for movement in the opposite direction.

United States Patent Clarke et al.

[ FLUID CYLINDER UNIT CUSHION STRUCTURE [75] Inventors: Evans L. Clarke, Sherrard, Ill.;

Joseph T. Kulhavy, Davenport, Iowa [73] Assignee: J. LCase Company, Racine, Wis.

[22] Filed: Apr. 9, 1973 [2]] Appl. No.: 348,977

[52] US. Cl. 91/395, 91/406' [51] Int. Cl. F15b 15/22 [58] Field of Search 91/395, 396, 409, 408, 91/407, 229, 406, 405, 394; 92/85 [56] References Cited I UNITED STATES PATENTS 2,987,047 6/1961 Young 91/395 3,361,036 l/1968 Harvey et al. 91/229 3,491,653 1/1970 Eastin 91/407 FOREIGN PATENTS OR APPLICATIONS 825,812 12/1971 France 91/395 [111 3,823,648 1 July 16, 1974 91,210 6/1961 Denmark 92/85 Primary Examiner-Paul E. Maslousky Attorney, Agent, or Firm-Arthur J. Hansmann 5 7] ABSTRACT A fluid cylinder unit cushion structure having a cylinder with a piston slidable therein against a stop to present a space between the head end of the cylinder and the piston. The fluid port is in the cylinder head end, and the piston carries a spring type of valve which seats over the fluid port when the piston is in its end limit position at the head' end. The spring also has clearance for moving off the fiuid port when the piston is in its end limit position and when the fluid pressure is reversed to get flow into the cylinder through the port and thereby return the piston for movement in the opposite direction.

1 6 Claims, 5 Drawing Figures l FLUID CYLINDER UNIT CUSHION STRUCTURE This invention relates to a fluid cylinder unit cushion structure, and, more particularly, it relates to a cushion structure which is under the influence of the fluid pressure in the unit to utilize the fluid pressure in cushioning the end limit movement of the piston.

BACKGROUND OF THE INVENTION As mentioned, this invention relates to the fluid actuated type of cushion structure, and, the prior art is already aware of fluid units which utilize the fluid pressure within the unit to cushion the movement of the piston toward its end limit and to thereby avoid an abrupt stopping of the piston. One example of such priorart is shown in U.S. Pat. No. 3,034,482 where a spring responsive member is movable with the piston and seats over a fluid port in the cylinder to dampen or cushion the movement of the piston as it approaches the fluid port at the end-of the cylinder. Another example of prior art is seen in U.S. Pat. No. 1,604,548.

Where the prior art devices are concerned about solving the problem of cushioning the movement of the piston and doing so by utilizing the fluid within the cylinder as the cushioning medium, the prior art devices are complicated and do not function in an efficient manner, both for the cushioning operation and also for permiting the fluid to return flow through the-port and enter the cylinder for reversing the direction of the piston.

Accordingly, it is an object of this invention to improve upon the fluid cylinder unit cushion structures of the nature referred to. More specifically, it is an object of this invention to provide a cushion structure which is efficient and reliable in dampening or cushioning the movement of the piston toward its end limit of travel, and which structure also permits re-entry of the fluid into the cylinder and to immediately be effective against the full face of the piston for movement of the piston without delay. In accomplishing these objectives, the structure of this invention utilizes the valve member which closes the fluid port as the piston is approaching its end limit of travel, and the valve member is also movable to open the fluid port when the piston is in its end limit of travel, to thereby permit the fluid to enter the cylinder and be effective against the full face of the piston for immediate movement of the pis- I011.

Still further, it is an object of this invention to accomplish the aforementioned objectives and to solve the problem referred to, and to do so with a unit which is simple but yet reliable and which can be readily and easily provided and maintained as necessary. That is, where this invention utilizes a valve member for closing the fluid port, no expensive valve closure is required and no special valve seat is even required for restricting or closing the flow of fluid from the cylinder in the cushioning process.

Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view through a head end of a cylinder unit, and showing a preferred embodiment of this invention.

FIG. 2 is a top plan view of a portion of the unit shown in FIG. 1, and with parts thereof in a slightly different position.

FIGS. 3, 4 and 5 are sectional views similar to FIG. 1 but with the parts thereof in different positions as seen therein.-

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The drawings show the fluid cylinder unit to include the fluid cylinder 10 with a piston 11 slidably disposed therein. A piston rod 12 is suitably attached to the piston 11, such as by the screw 13 which has its head portion 14 and a washer 16 over the piston face 17, and which has its threaded shank portion 18 threaded into the piston rod 12, as shown. The cylinder 10 also has a head 19 which has a fluid passagewayZl and a fluid port 22 which extends into an opening 23 in the head 19 so that fluid can flow to and from the opening 23 via the port 22. The cylinder head 19 presents a shoulder 24 which serves as an end limit or stop since it is in the path of theforward or head end movement of the piston 11, so the piston 11 can come against the stop 24, as shown in FIG. 4. I

It will therefore be understood that the piston 11 is snugly slidably disposed within the cylinder 10, and the rod 12 extends from the cylinder 10 to connect to a work piece or implement, in the usual manner. That is, a force on the rod 12, or a fluid force on the right side of the piston 11, will cause the piston 11 to move to the left from the position shown in FIG. 1 to the position shown in FIG. 3 and finally to the position shown in FIG. 4, where it is against the stop24. The purpose of the present invention is to cushion the movement of the piston as it approaches the stop 24 so that it does not impact upon the stop 24. To this end, the structure of this invention is provided to present a valve means which is operative over the fluid port 22 to restrict the flow of fluid out the port 22 and thereby effect the cushioning for the end limit movement of the piston 11. That is, where a liquid is the fluid medium, such as hydraulic oil, the flow of the oil out the port 22, in the direction of the arrows designated A in FIG. 1, will be restricted by the valve means of this'invention, and thus the-piston 11 will be cushioned in its end limit movement. To do this, the valve means of this invention is a valve member generally designated 26 and having a portion 27 affixed to the head end of the piston 11 through a screw 28 extending into the piston screw 14. The valve 26 also has a-closure portion 29 which extends away from the piston 11 and the piston screw 14 in the free position of the valve member 26 as seen in FIG. 1. The drawings further showyand particularly FIG. 2 shows, that the valve member 26 isa piece which is countersunk into a groove 31 in the head of the screw 14, and thus the valve member 26 is assured of attachment and alignment with the piston 11, and thus the valve closure portion 29 will always align with the fluid port 22 to close thereover as shown in FIG' 2. The drawings further show that the valve member 26 is generally V-shape in its unstressed condition and is of a flat spring material having its two opposite legs 27 and 29 joined through the common or central portion 32.

Thus, it will be seen and understood that as the piston 11 approaches the stop 24, but before it actually gets to thestop 24 in the FIG. 4 position, the valve member sure 29, as shown by the arrows B in FIG. 4, and this causes sufficient and efficient cushioning of the move- .ment of the piston 11 toward the stop 24. Of course the member'26 is of sufficient spring material and resiliency so that it can move from its unbiased condition shown in FIG. 1 and to its biased condition shown in FIGS. 3 and also in FIG. 4. In theinterim, FIG. 3 shows the arrow C which indicates the final escape of fluid from the chamber 23 as the fluid pressure would be developing higher in the chamber 23 to create the desired cushioning force for the leftward movement of the piston 11.

Thus an inexpensive, simple, but yet highly reliable valve arrangement is provided, and the closure 29 is wider than the fluid port 22 so that it will fully cover the port 22, and the port 22 is axially of the cylinder unit so that, regardless of the rotation of the screw 14, the valve member closure portion 29 will always cover the port 22. Still further, the arrangement does not require any valve seat as such at all, and the closure 29 simply extends over the port 22 and along the wall 33, as described and shown, and the fluid pressureitself actually serves to secure the valve member in sufficient closed position to assure the cushioning effect desired, as described in connection with the arrows C and B in FIGS. 3 and 4, respectively.

Still further, when it is desired to reverse the flow in the port 22 to actually have the fluid enter the cylinder and move into the chamber 23, in the direction of the arrows D shown in FIG. 5, then thevalve closure portion 29 will simply move off the port 22, as shown in FIG. 5. That is, there is sufficient space between the cylinder end wall 33 and the plane designated 34 which is along the surface of the valve portion 27 and along the head surface of the milled or slotted screw 14. Therefore, the valve closure portion 29 has room in which to flex to the position shown in FIG. 5, and of course such would not be the case if the plane 34 extended up to the valve closure portion 29 in the end limit position shown in FIG. 5. With this arrangement of the valve member 26 opening upon return flow, the return flow can be immediately available and fully effective to apply against the full projected surface of the head end of the piston 11, rather than apply only against an area as large as the area of the port 22. Therefore, the full incoming fluid pressure in the direction of the arrows D will immediately be effective on the full piston area to immediately move the piston without sluggishness or delay. In accomplishing this, the V-shaped valve member 26 is flexible, so that it closes the port 22, under the influence of the fluid pressure leaving the chamber 23, and it immediately opens the port 22, under the influence of the fluid pressure entering the chamber 23, both actions being for the desirable purposes mentioned.

In the configuration of the valve member 26, it will also be seen and understood that while the portion 29 extends away from the attached and opposite leg'por' tion 27, as shown in FIG. 1, the member 26 is arranged so that its closure portion 29 can also extend in a plane on the end wall 33, when the parts are in the position shown in FIG. 4, so that the entire port 22 is closed in the FIG. 4 position as the leg or portion 29 is parallel with the wall 33 by virtue of the flexibility of the member 26 and the hairpin arrangement at the common juncture 32, and therefore the wall 33 presents the valve seat for the closure portion 29. Therefore, the legs 27 and 29 are parallel in the closed position shown in FIG. 4, and the valve closure 29 and wall 33 are angularly disposed relative to each other when the closure 29 is not in the closed position.

Further, as seen in FIG. 2, there may be a hole 36 extending through the closure portion 29 to permit limited escape of fluid from the chamber 23, and the hole 36 may be of a selected size to produce a predetermined pressure drop, if retardation of the piston motion is otherwise too severe.

What is claimed is:

1. A fluid cylinder unit cushion structure comprising a cylinder with an end wall at one axial end of said cylinder and having a fluid port in said end wall, a piston slidably disposed in said cylinder, an end limit stop in said cylinder and engageable with said piston and spaced from said end wall for limiting movement of said piston toward said end wall, a valve member attached to said piston for movement therewith and including a closure'portion positioned on said end wall and over saidfluid port for restricting the flow of fluid from said cylinder when said piston is near and at the end limit of its movement, said closure portion being movably attached to said piston for movement off said end wall to open said fluid port to the reverse flow of fluid, while said piston is still engaged with said end limit stop, for allowing the reverse flow of fluid to pass said closure portion and reach said piston to force on said piston for the return movement of said piston, said closure portion being disposed at an angle to said end wall with said fluid port when not fully seated on said end wall, to only gradually close said fluid port when said piston is approaching said end limit stop, for cushioning the stopping of said piston.

2. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said valve member is a spring member attached to said piston at one portion of said spring member, and extending away from said piston at another portion of said spring member to present said closure portion spaced from said piston.

3. The fluid cylinder unit cushion structure as claimed in claim 2, wherein said spring member is a flat spring piece disposed in a V-shape with one leg thereof attached to said piston and the other leg thereof serving as said closure portion and being of a length to contact said end wall when said piston is spaced from said end limit stop.

4. The fluid cylinder unit cushion structure as claimedin claim 1, wherein said spring member is a flat spring piece disposed in a V-shape with one leg thereof extending beyond the head end of said piston toward said fluid port for covering over said fluid port before said piston reaches the end limit of its travel, and with said one leg being spaced from and movable toward said piston, under return flow of fluid, to uncover said fluid port and allow the return flow to act on said piston f forimmediate return movement of said piston.

5. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said end wall of said cylinder is aligned with the longitudinal axis of said cylinder, and said port has its central axis parallel with the longitudinal axis of said cylinder, and said valve closure is 6 flexible to a planar position along said end wall and fluid passageway therein for the flow of fluid relative to over said port. the interior of said cylinder when said valve closure is 6. The fluid cylinder unit cushion structure as positioned on said fluid port. claimed in claim 1, wherein said closure portion has a 

1. A fluid cylinder unit cushion structure comprising a cylinder with an end wall at one axial end of said cylinder and having a fluid port in said end wall, a piston slidably disposed in said cylinder, an end limit stop in said cylinder and engageable with said piston and spaced from said end wall for limiting movement of said piston toward said end wall, a valve member attached to said piston for movement therewith and including a closure portion positioned on said end wall and over said fluid port for restricting the flow of fluid from said cylinder when said piston is near and at the end limit of its movement, said closure portion being movably attached to said piston for movement off said end wall to open said fluid port to the reverse flow of fluid, while said piston is still engaged with said end limit stop, for allowing the reverse flow of fluid to pass said closure portion and reach said piston to force on said piston for the return movement of said piston, said closure portion being disposed at an angle to said end wall with said fluid port when not fully seated on said end wall, to only gradually close said fluid port when said piston is approaching said end limit stop, for cushioning the stopping of said piston.
 2. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said valve member is a spring member attached to said piston at one portion of said spring member, and extending away from said piston at another portion of said spring member to present said closure portion spaced from said piston.
 3. The fluid cylinder unit cushion structure as claimed in claim 2, wherein said spring member is a flat spring piece disposed in a V-shape with one leg thereof attached to said piston and the other leg thereof serving as said closure portion and being of a length to contact said end wall when said piston is spaced from said end limit stop.
 4. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said spring member is a flat spring piece disposed in a V-shape with one leg thereof extending beyond the head end of said piston toward said fluid port for covering over said fluid port before said piston reaches the end limit of its travel, and with said one leg being spaced from and movable toward said piston, under return flow of fluid, to uncover said fluid port and allow the return flow to act on said piston for immediate return movement of said piston.
 5. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said end wall of said cylinder is aligned with the longitudinal axis of said cylinder, and said port has its central axis parallel with the longitudinal axis of said cylinder, and said valve closure is flexible to a planar position along said end wall and over said port.
 6. The fluid cylinder unit cushion structure as claimed in claim 1, wherein said closure portion has a fluid passageway therein for the flow of fluid relative to the interior of said cylinder when said valve closure is positioned on said fluid port. 